Product and process for the prevention of foaming in steam boilers



Patented Oct. 14, 1947 PRODUCT AND PROCESS FOR THE PREVEN- TION OFFOAMING IN STEAM BOILERS Paul G. Bird, Western Springs, Ill., assignorto National Aluminate Corporation, Chicago, 111., a corporation ofDelaware 7 e No Drawing. Application March 27, 1942,

Serial No. 436,488

8 Claims. (Cl. 252-321) 1 The present invention relates to antifoamingcompositions which are used in steam boilers and similar steamgenerators, evaporators, etc., to

overcome the tendency of the water therein to foam and hence to bringabout the priming of the steam generator or the like.

One of the objects of the present invention relates to a liquid suitablefor the generation of steam in steam generators, comprising watercontaining dissolved therein a very small quantity of a particular kindof a high molecular weight acyla-mino-N-alkylated amide, whereby, whensuch water is heated to the boiling point in a steam boiler or othergenerator, being thereb evaporated, the concentration of solids thereinwill not bring about excessive foaming and the resulting priming, thesecompounds being substantially nonvolatile with the steam and stable, sothat they will be retained by the water and .neither they nor theirdecomposition products will appear in the steam and the resultingcondensation thereof.

It is well known in the operation of steam boilers, such as in electricpower plants, railroad locomotives and the like, or in evaporators, thatthe water therein, even though initially it shows very little tendencyto foam, will, when the amount of total solids therein approaches arelatively high concentration, develop a very decided tendency to foam.When this occurs, considerable quantities of water are physicallycarried out of the boilers or evaporators with the steam, thus appearingin the steam lines and in the eventual condensate. Such priming has manydisadvantages because it tends to contaminate the steam lines, to plugor corrode the valves, and under serious conditions may even impair thecylinders and piston rods of the steam engines, or the impeller bladesof turbines in which the steam is used for the generation of power.Attempts have been made in the past to control this foaming, either byexcessive blow-down of the boilers or by the injection thereinto of suchmaterials as castor oil, tallow, and the like. While these fattymaterials have some small degree of efiiclency, they are, on the otherhand, quite deficient in that they introduce new difliculties which, insome instances, are worse than the conditions they are intended to cure.In the first place, these fatty acids or glycerides are unstable underthe conditions existing in the boilers, particularly as the pressure andtemperature'increase, the high temperatures leading to rapiddecomposition of the glycerides, which, if anything, will tend toincrease the foam and priming dimculties. Furthermore, in many instancescertain of the decomposition products 'thus produced, or sometimes eventhe materials themselves, have a definite volatility with steam andwill, therefore, steam-distil out of the boilers, thus appearing in thesteam and in the condensate. This, of course, is also very undesirable.Furthermore, such types of antifoaming agents usually have to beemployed in relatively large quantities, adding not only to the expensebut also to the inconvenience of operating the steam generators; andthose which have a tendency to decompose do so quit-e rapidly, and hencetheir effectiveness is of short duration, which therefore necessitatesthe continual charging into the boilers or other steam generators ofrelatively large amounts of these older antifoaming agents. Moreover,such antifoaming agents are difficult to use because the amounts inwhich they are efl'icacious are very critical, and any overdosageusually aggravates the difficulty instead of curing it.

Applicant has now discovered, however, that there is a series ofcompounds which may be broadly designated as acylamino-N-allqrlatedamides, which are condensation products derived from aminoacids, organicacids and organic amines, and which are very efficacious in overcomingthe priming and foaming of boilers, etc., containing dissolved solids.

The products which are employed in the prevention of foaming and primingmay be considered as complex derivatives or reaction products of anaminoacid which has reacted with an organic acid or acid derivative andwith an aliphatic primary or secondary amine, in any desired order,whereby the amino group of the aminoacid becomes acylated and the acidgroup of the aminoacid is converted into an N-alkylated amide group.Such compounds can broadly be designated as acylamino-N-alkylatedamides, an example of which would be a material such aspalmitylamino-N-hexadecylcaproamide.

The probable general structural formula for the materials of thisinvention may be written:

OCANHZ RI wherein R and R are the alkyl groups from an aliphatic amine,and either R or R, but not both, may be hydrogen; Z is the acyl radicalof an organic monobasic acid; and A is the alkylene or arylene residueof an aminocarboxylic acid. It is to be understood that the formulasrecited in the claims are "probable" in that the formulas I use ofthese.

given are believed to be possessed by the compounds disclosed, or whosemethod of preparation is disclosed, in this specification.

Some specific examples of materials of the above description, which havebeen shown to be of value, are (1) the product resulting from thereaction of palmityl chloride on epsilon-aminon-caproic acid, followedby treatment with noctadecylamine; (2) the product resulting from thereaction of palmityl chlorideand alphaamino-n-valeric acid, followed bytreatment with n-hexadecylamine; (3) the product resulting from thereaction of palmityl chloride and alpha-amino-n-butyric acid, followedby treatment with n-hexadecylamine; and (4) the product resulting fromthe reaction of palmityl chloride and p-aminophenylacetic acid, followedby treatment with n-hexadec-ylamine; all as more fully described in theexamples given hereinbelow.

Investigation has shown that an,important factor iii/determining whetherthe materials of this invention are valuable as anti-foaming agents isthe number of carbon atoms in the derivative. Thus it appears that, tobe of value, the derivative should contain at least about 36 carbonatoms. It will be apparent that this can be readily realized throughtheuse of relatively high molecular weight fatty acids and fatty amines,although the invention is not restricted to the the amino group of theaminoacid by an aromatic or arylsulfonic acid or derivative thereof.

The following examples are given to show how some valuable materials ofthis invention may be made, but the examples are not intended to limitthe scope of the invention beyond the claims themselves.

Actually, it is possible to acylate Example 1.To 19.5 grams of palmitylchloride at 130 C., 5 grams of epsilon-amino-ncaproic acid was addedwithstirring. The mixture-was stirred at 150-160 C..for an hour, after which10.2 grams of n-octadecylamine was added and stirring and heatingcontinued 2 hours longer. When cool, the product was a brown wax and canbe termed as a palmitylamino-Ne octadecylcaproamide.

E:1:ample a-TO 11 grams of palmityl chloride st'antially devoid offoaming and priming which may be termedpalmitylamino-N-hexadecylbutyramide.

Example 4.'11 grams of palmityl chloride and 6.1 grams ofp-aminophenylacetic acid" were caused to react by mixing and heatingtogether for 30 minutes at 250 C. Then 9.6 grams of n-hexadecylaminewas'added and the mixture stirred one hour at 200 C. The resultingproduct was a very hard, brown wax-like material, and can be consideredas being palmitylamino-N- hexadecylp-aminophenylacetamide.

These 'acylamino-N-alkylated amides may be suitably dispersed in wateror emulsified therewith, so that eflfective amounts thereof may beintroduced and be present in the water within a the steam generatorunder operating conditions.

The emulsifying or dispersing agent used must, however, be of a kindthat does not cause foaming, either by itself or by its decompositionproducts. The compounds may be used conjointly with each other as wellas with other known antifoaming agents, such as, for example, castoroil.

The amounts required of these acylamino-N- alkylated amides of thepresent invention are extremely small, and in general one grain pergallon is ample. For many purposes, however, amounts of as little as1/100 grain per gallon in the feed water will still give valuableresults, and the amounts maybe even further reduced. Depending of courseupon the degree of concentration of solids, the dosage may be varied,but one grain per gallon is about as much as would ever have to be usedeven under serious conditions,

'and for many purposes 1/ grain per gallon and even less can be used.The process is particularly efiective at pressures of about 250 poundsper square inch.

The introduction of the antifoaming compounds of the present inventioninto the boiler maybe accomplished in a number of ways. Thus, theantifoaming compositions may be dispersed or physically mixed with, say,sodium carbonate of the anti-foaming compounds into the feedwater may beused, so that the introduction will be more or less in proportion to thesteam consumption to which the steam generator is subjected. Anothermanner of introducing the antifoaming compounds is to form an emulsionthereof in water and then feed said emulsion 'either directly into theboiler or the feed water lines leading to it. The invention therefore isnot to be limited by the manner of introductionv of the antiioamingcomposition but rather is to be construed in'the terms of the hereuntoappended claims.

I claim:

1. A liquid for the generation of steam, subtendencies when heated tothe boiling point, comprising water containing an amount of total solidstending to produce foaming and priming and having dispersed therein aquantity of an acylamino-N-alkylated amide sumcient to substantiallyinhibit priming and foaming, said amide having at least 36 carbon atomsand having the general formula from the group consisting of alkylene andarylene.

2. A liquid for the generation of steam, substantially devoid of foamingand priming tendencies when heated to the boiling point, comprisingwater containing an amount of total solids tending to produce foamingand priming and having dispersed therein a quantity ofpaimitylamino-N-octadecylcaproamide suflicient to substantially inhibitpriming and foaming.

3. A. liquid for the generation of steam, substantially devoid offoaming and priming tendencies when heated to the boiling point,comprising Water containing an amount of total solids tending to producefoaming and priming and having dispersed therein a quantity ofpalmitylamino-N-hexatiecyivaieramide sumcient to sub stantiaily inhibitpriming and foaming.

4. A liquid for the generation of steam, su stantiaiiy devoid of foamingand priming tendencies "when heated to the boiling point, comprisingtvater containing an amount of total solids tending to produce foamingand priming and having dispersed. therein a quantity ofpalmitylamino-N-herradecyihutyramide sumcient to substantially inhibitpriming and foaming.

5. Process oi minimizing the production of foam in and the priming ofsteam generators operating at superatmospheric pressures which comprisesincorporating with a water therein containing an amount of total solidstending to produce foaming and priming a quantity of anacyiamino-N-alkyiated amide suficient to substantially inhibit primingand foaming, said amide having at least 36 carbon atoms and having thegeneral formula in which R and R are the alkyl groups from an aliphaticamine, and either R or R, but not both;

may be hydrogen; Z is an acyl radical of a monocontaining an amount oftotal solids tending to produce foaming and priming a quantity ofpalmitylamino-N-octadecylcaproamide sumcient to suppress priming andfoaming.

7. Process of minimizing the production of foam in and the priming ofsteam generators operating at superatmospheric pressures which comprisesincorporating with a water therein containing an amount of total solidstending to produce foaming and priming a quantity ofpalmitylamino-N-hexadecylvalerarnide sumcient to suppress priming androaming.

8. Process of minimizing the production of foam in and the priming ofsteam generators operating at superatmospheric pressures which comprisesincorporating with a water therein containing an amount of total solidstending to produce foaming and priming a quantity ofpalmitylamino-N-hexadecylbutyramide eufiicient to suppress priming andfoaming.

PAUL G. BIRD.

REFERENCES QETED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,892,857 Spellmeyer Jan. 3, 19332,304,805 Denman Dec. 15, 1942 Gunderson Sept. '7, 1943

